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I'm a beginning music theory student and often when I'm supposed to be doing exercises I get distracted and start doodling around for fun on the black keys. It's easy to compose simple, satisfying melodies on them, but I don't know the underlying theory and practice.

  1. Is there a name for this pentatonic scale? (NB - the accepted answer to this question Difference between keys and scales? said that the terms 'mode', 'scale' and 'key' are often used interchangeably by musicians, so what's the best term to refer to the black keys?)
  2. I notice that when I'm doodling on them, no matter what note I start with it often likes to come to rest on G♭; that seems to be a tonic note. Why?
  3. What are the rules/guidelines for harmonising with black key melodies? When I listen to other music using the black keys, the chords are seldom purely diatonic but are there useful guidelines for writing chords to harmonise black key melodies?
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The black keys on the piano are exactly what you said, pentatonic scales. Which scale it is depends on what you use as your tonic or focus note. You mentioned G♭, the black keys are a G♭ (or F♯) major pentatonic scale. Add the white keys C♭ (B) and F and you have a full blown G♭ major scale. The pentatonic scale removes the 4th and 7th degrees of the major scale.

It is also an E♭ (or D♯) minor pentatonic scale if you change your tonic/focus to E♭. E♭ minor is the relative minor of G♭ major so they use the same notes. The 2nd and 6th degrees of the minor scale are removed for the minor pentatonic scale. Try playing the black keys over Stevie Wonder’s “Superstition”, (it’s in E♭ minor) you can’t go wrong!

Often melodies are exclusively or at least very pentatonic. Harmony however more often but not exclusively follows the guidelines of the 7 chords created from the major and minor scales.

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    ...and F (E#)... completes it.
    – Tim
    May 13 at 18:23
  • The example I always gave was "My Girl" from the Temptations. Apparently pentatonic scales were kind of a thing in that genre of music? Hadn't noticed it with "Superstition" before, but yeah, it's there. Now I'm gonna have to listen more closely to other such artists - Did Marvin Gaye, the Four Tops, the Supremes, Pointer Sisters, et al. sneak pentatonic scales in there? Funny because you usually associate that with far eastern music... May 14 at 19:56
  • Pentatonic scales are easy and ubiquitous on guitar. Any genre with a lot of guitarists will probably make frequent use of pentatonic scales. May 15 at 6:41
  • @DarrelHoffman “What’s Going On” is almost completely pentatonic. Many blues, rock, pop and r&b melodies are largely based on either major or minor pentatonic scales, not to mention the fact that they are used quite a bit for instrumental solos in those styles. May 15 at 7:36
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You would call it a pentatonic scale. You are centering it around G flat, so it's specifically a major pentatonic scale.

It depends how you work the melody, but lots of pentatonic melodies "work" because the scale can be thought of as outlining a tonic chord with two auxiliary notes, one a whole step above the tonic and another a whole step above the fifth. In other words it is Gb Bb Db - a major triad tonic chord - plus an Ab above Gb and an Eb above the Db.

Compared to a major scale the major pentatonic scale lacks the tones FA and TI. The result is the dissonant interval of the tritone doesn't exist in pentatonic scales. Similarly there are no half steps so can't have minor seconds either. Both intervals are traditionally considered very dissonant. Their absence means pentatonic scales are comparatively consonant to other scales. If you have ever held down the sustain pedal, noodled on a pentatonic scale, and though all the sustained tones sound nice, you're hearing this consonant aspect of the pentatonic scale. (Do the same sustain pedal trick with other scales and by comparison those other scales will probably sound noisy and dissonant.)

In terms of harmony the tonic major chord and its relative minor can be played with complete triads using the tones of a pentatonic scale, and those tow chords can be thought of as the fundamental harmonies of pentatonic music. In Gb the two chords are Gb major and Eb minor, or the I and vi chords.

The pentatonic scale doesn't include the tones to make complete triads for chord IV or V - in Gb major the Cb and Db chords. But it's very common to accompany a pentatonic melody with the full chords. In other words it's common to play something like a Gb major pentatonic melody while accompanying it with basic chords like I IV V from Gb major.

I notice that when I'm doodling on them, no matter what note I start with it often likes to come to rest on G♭; that seems to be a tonic note. Why?

It's a little tricky to describe but when the tones are arranged as Gb Ab Bb Db Ed it's easy to see the complete tonic chord Gb Bb Db where Gb is then heard as the tonic. If you start on another tone you don't have a complete tonic chord, ex. Ab Bb Db Eb Gb and Ab (no Cb) Eb, so that makes a kind of "weak" candidate for a tonic of Ab. The same happens with the other tones, except the Eb. If you start there you get Eb Gb Ab Bb Db and there is a complete minor triad for a tonic Eb Gb Bb, and with an Eb tonic this will be the minor pentatonic scale. If you try noodling on that you should hear a satisfying minor pentatonic sound and Eb tonic. Perhaps you prefer the major mood over the minor, but you should be able to hear Eb as a solid minor tonic.

Just in case it isn't already understood, this pentatonic aspect is a special property of the black keys. It's visually and tactilely easy to see and feel a pentatonic scale with only the black keys, but you can play pentatonic scales on other keys too. For example, C D E G A, E F# G# B C#, Bb C D F G, etc. etc. are pentatonic scales on other tonics.

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This scale is simply called the major pentatonic scale. It is build using the 1,2,3,5 and 6 of the major scale.

For example in C (major) the scale tones are C, D, E, F, G, A, B. If you you take the 1,2,3, 5 and 6 you get C, D, E, G and A. Thats the C major pentatonic

When you are only using the black keys you often like to rest on Gb, that's because the black keys are the 1,2,3,5 and 6 of the Gb major scale.

The major pentatonic scale is very easy to use, because each note will sound good with each other. There are no "wrong" or "strange" sounds in the scale. It's very mighty tool for creating melodies. The only flaw is that it can become monotonous. Thats also because every note will sound good with each other. If you use only the pentatonic scale you might be missing some of the spice these "strange" sounding notes can give you.

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Is there a name for this pentatonic scale?

The black keys can be used to construct several pentatonic scales, depending on which of them you consider the number 1 note. If you start from Gb (or F#), it's called the Gb (or F#) major pentatonic scale. If you start from Eb (or D#), it's called the Eb (or D#) minor pentatonic scale.

what's the best term to refer to the black keys?)

If you want to refer to the black keys specifically, in an absolute sense, you can call them simply the black keys, and most people will know what you mean, even those who don't know what "pentatonic" means. If you want to refer to pentatonic scales, and not necessarily Gb major or Eb minor pentatonic scales, then call it a pentatonic scale.

I notice that when I'm doodling on them, no matter what note I start with it often likes to come to rest on G♭; that seems to be a tonic note. Why?

That's because you instinctively imagine harmonies where the tonic is Gb major. And that's because you have heard so much music that's structured that way. But it depends on your personal history and experiences and it doesn't have to be that way - when I started doodling with the black keys as a child, I always imagined Eb minor to be the tonic, because most pop music I had heard and liked, was in a minor key. Melancholic stuff.

What are the rules/guidelines for harmonising with black key melodies? When I listen to other music using the black keys, the chords are seldom purely diatonic but are there useful guidelines for writing chords to harmonise black key melodies?

If you mean, "please list all the things that can be done with pentatonic scales", then the internet will run out of storage capacity before we get the question done.

First of all, an important feature about pentatonic scales is that when played over the scale's corresponding tonic chord, the played notes align with the tonic chord without being able to imply a dominant chord, unless the backing chords play a dominant (on the scale's fifth degree). The Gb major pentatonic scale does not have the two notes that are needed for this in Gb major: F and Cb. If you add those, you get the full Gb major scale.

Pentatonic scales (the ones that are structured like the black keys) fit over a lot of things. I would categorize the different styles of usage to two categories:

  • (1) Riding an existing harmony and chord progression, supporting the harmony without really "disagreeing" with it. Maybe emphasizing some notes at most. In this style you place the pentatonic scale over the tonic, for example if the song is in Gb, you play the black keys of the piano. This reinforces the already existing tonic.
  • (2) Twisting an existing harmony to new directions by overlaying things from "other keys".

Examples of the second style.

  • If the song is in Eb major (three flats in the key signature), you play the black keys (six flats in the key signature). This mixes major and minor in a bluesy/jazzy/soulful way.
  • If the song is in C# minor, and doesn't happen to use the A note at that point, you play the black keys (D# or Eb minor pentatonic scale), which include the A# note which is non-diatonic for C# minor. This brings a C# Dorian feel, shifting the sixth note, A natural (that you have in C# natural minor) to A#. Or if you want to see the same pattern in another key, if the song is in C minor and doesn't use the Ab note at that point, you play the D minor pentatonic scale (D F G A C) to create a C Dorian feeling.

This is just my speculation, but I think one of the main reasons why pentatonic scales are so useful for playing "outside" is that people are so familiar with (playing and hearing) note sequences that use pentatonic scales. The familiarity allows players to rhythmically and technically cleanly and precisely execute lines using those scales. When the lines are so clear, the ear goes to "pattern matching" mode and tries to recognize what's happening - and since that differs from what the ear thought to be the prevailing harmony, this creates an interesting "outside" feeling. Which is not the same as random chaos.

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This answer is from Indian music theory (I see that there are many good and complete answers from Western music theory already).

Taking each key as the tonic, you get different modes of the pentatonic scale.

  1. C♯ – Taking C♯ as the tonic, you get the mode corresponding to the raga Shuddha Saveri/Durga. Transposing to C, the scale is C D F G A.

    Shuddha Saveri on Veena by Jayanthi Kumaresh (Tonic: E)
    Durga played on Sarod by Debasmita Bhattacharya (YouTube) (Tonic: C, approximately — maybe due to some issue with the recording, I feel that the actual tonic we hear in this is slightly sharper than C.)

  2. D♯ – Transposing to C, the scale is C E♭ F G B♭, which is the minor pentatonic, and corresponds to the mode of the raga Shuddha Dhanyasi/Dhani (Wikipedia has incorrectly merged the pages of Shuddha Dhanyasi and Udayaravichandrika pages, but these are two different ragas. In Carnatic notation, the former has N₂, and the latter has N₃ instead). I have also heard this mode being used in a song that was very common in many Kung Fu movies — Example (Tonic: A♯).

    Shuddha Dhanyasi on Violin by MS Gopalakrishnan (YouTube) (Tonic: E) (Skip to 5:23 to get to the composition, after the aalaap [raga elaboration].)
    Dhani (vocal) by Srijan Deshpande (Facebook) (Tonic: D)

  3. F♯ – Transposing to C, the scale is C D E G A, which is of course the most familiar major pentatonic. This corresponds to the mode of the raga Mohanam/Bhoop. This raga is one of the oldest and most popular in Indian music. It is also popular, as far as I understand, in Chinese classical music, and is often featured in Hollywood movies as Chinese music.

    Mohanam on Flute by N Ramani: Aalaap and Composition (Nannu Palimpa) (Tonic: D♯)
    Bhoop on Sarangi by Sultan Khan (Tonic: E, but again, I feel it's slightly off.) (Skip to 17:40 for the composition.)

  4. G♯ – Transposing to C, the scale is C D F G B♭, which corresponds to the raga Madhyamavati/Madhmad Sarang.

    Madhyamavati by M Balamuralikrishna (Tonic: C) (Skip to 21:09 for the composition.)
    Madhmad Sarang on Violin by N Rajam (Tonic: E)

  5. A♯ – Transposing to C, the scale is C E♭ F A♭ B♭, which corresponds to the raga Hindolam/Malkauns.

    Hindolam on Electric Mandolin by U Srinivas (Tonic: C) (Skip to 12:01 for the composition.) Malkauns on Flute by Hariprasad Chaurasia (Tonic: E)

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Is there a name for this pentatonic scale?

Well, the black keys themselves don't necessarily make a unique scale by themselves.

To show you what I mean, all of the black keys are in the B major scale. However, the same is also true of the F# Major scale (or the Gb Major scale if you like to use flats instead). So it kind of depends on the context you're using them in.

However, since you mention a pentatonic scale, I'm assuming you're interested if there is a scale that has just the 5 black keys in it, and nothing else. In that case, you're in luck. The Gb Major Wikipedia article has something interesting on that:

In particular, the black keys G♭, A♭, B♭, D♭, and E♭ correspond to the 5 notes of the G-flat Pentatonic Scale

So the name you're looking for is probably the Gb Pentatonic Scale.

[W]hat's the best term to refer to the black keys?

Again, it really depends on the context you're using it in. However, I think "scale" is probably the appropriate term here. Actually, "pentatonic scale" is probably the more appropriate term here since there are only 5 notes in the scale.

I'm not going to re-hash here the differences between "modes", "scales", and "keys". The other question you reference does a good job of explaining the differences in my opinion (or at least it does a better job at explaining them than I could do explaining them here). If you are still confused after reading that question, perhaps it might be a better idea to ask about that confusion in more detail in a separate question.

I notice that when I'm doodling on them, no matter what note I start with it often likes to come to rest on G♭; that seems to be a tonic note. Why?

This to me says that, again, you're probably using the Gb Pentatonic Scale. Gb is in fact the tonic note of that scale, and that's probably what your ears are picking up on.

What are the rules/guidelines for harmonising with black key melodies? When I listen to other music using the black keys, the chords are seldom purely diatonic but are there useful guidelines for writing chords to harmonise black key melodies?

That's probably too broad of a question to do justice here, but the short answer is probably the same as with white keys.

Music theory in general doesn't usually differentiate between "white" and "black" keys; music theory usually deals with scales. That is to say that it doesn't really matter if you are using white keys or black keys, but rather if you're using a major scale, minor scale, pentatonic scale, or other type of scale.

So, what are those rules exactly for each of those types of scales? I couldn't tell you. I barely have a handle on major scales; I certainly couldn't tell you about rules for minor or pentatonic scales. That's just knowledge I don't currently have. But I can tell you that type of scale probably makes a lot more of a difference than if the keys are white or black.

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    Classical music theory doesn't much deal with scales. It is far more concerned chords and keys.
    – phoog
    May 13 at 19:42

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